What type of insulation is best for my home?

Fiberglass batts are affordable and good for open attics and walls during construction. Blown-in cellulose works well for attic floors and existing wall cavities. Spray foam provides the highest R-value per inch and seals air leaks, making it ideal for rim joists, crawl spaces, and irregular spaces. Rigid foam boards are great for basement walls and exterior sheathing. The best choice depends on your budget, location, and installation access.